The present invention relates to a lamp device for vehicle such as a vehicle headlamp and a vehicle fog lamp for illuminating ahead of a vehicle. More particularly, this invention relates to the lamp device for vehicle with a light distribution function imparted mainly to a reflector side.
Lamp device for vehicles lately have a light distribution function imparted to a reflector side by shaping a reflecting surface of the reflector as a free curved surface. The latest lamp device for vehicles use so called permeable lens as a lens and have an outer cover function in the lens side. This permeable lens is not provided with a prism for light distribution, so that light passes through the lens as it is without refraction. That is, the permeable lens is formed of a plate-like (flat plate or curved plate) light transmitting member such as only a simple plate glass.
In the conventional lamp device for vehicles, however, the internal reflecting surface of the reflector is clearly seen through the permeable lens from the outside. Therefore, the conventional lamp device for vehicles require giving a finish more than optical performance required for reflection to the reflecting surface of the reflector, which is for the purpose of enhancement of its appearance, so that the machining work is complicated.
To solve the problem, the inventor of this invention has invented a lamp device for vehicle (Japanese Patent Application No. 11-209331 (Japanese Patent Application Laid-Open No. 2001-35215)) by which the interior is harder to be seen as compared to the permeable lens.
It is an object of this invention is to provide a lamp device for vehicle, by which a surface finish is more easily given to the reflecting surface of a reflector than the conventional way by making the interior harder to be seen as compared to the permeable lens.
It is another object of this invention to provide a lamp device for vehicle whose lens is easily polished when it is made of glass by forming the shape of the lens to be flat in vertical cross section or transverse cross section, which is excellent in manufacture of the lens.
In order to achieve the objects, this invention provides a lens having a concave shape or a convex shape in either one of vertical cross section and transverse cross section while having a flat shape in the other one of these sections.
As a result, this invention provides the lens that forms a concave shape or a convex shape in either one of vertical cross section and transverse cross section, and thereby the interior is harder to be seen because the light passing through the lens is largely refracted even if a prism is not provided. This invention does not therefore require giving a finish more than optical performance required for reflection to the front surface of the reflecting surface of the reflector, which is for the purpose of enhancement of its appearance, and thereby the machining work is simpler than the conventional way.
In this invention, the lens has a flat shape in the other one of vertical cross section and transverse cross section. Therefore, the lens, which is made of glass, can be easily polished and is therefore excellent in its manufacture.
Other objects and features of this invention will become understood from the following description with reference to the accompanying drawings.